Railway track circuit apparatus



I April 25, 1944.

N. F. AGNEW ET AL 2,347,533 RAILWAY TRACK CIRCUIT APPARATUS Filed July31, 1941 INVENTORS A bPmanEA 129w and THEIR A'iTORNEY Patented Apr. 25,1944 UNITED STATES FATENT OFFICE RAILWAY TRACK CIRCUiT APPARATUS vaniaApplication July 31, 1941, Serial No. 404,823

Claims.

Our invention relates to railway track circuit apparatus, and it hasparticular reference to the organization of such apparatus into noveland improved railway track circuits. More particularly, our inventionrelates to railway track circuits incorporating apparatus arranged to beindependent of variations in track ballast resistance.

Railway track circuits have been proposed heretofore incorporatingrelays arranged to eifect operation of their contacts only in responseto rapid changes in the track circuit energy received by the relays, aswhen a train enters'or leaves a track circuit, but not in response togradual changes in the relay energization eiiected due to changes intrack ballast resistance caused by atmospheric conditions, etc. In suchsystems, the relays employed have been designed to adjust their releaseenergy levels in accordance with existing ballast resistance conditions,while the pick-up energy levels of the relays are determined inaccordance with the ballast conditions existing at the time the relaysbecome released. When a train enters such a circult adjusted forextremely dry (or high resistance) ballast, and during the occupancy ofthe circuit, the ballast resistance varies and becomes lower due, forexample, to an extremely heavy. rainfallfthere is a'possibilit'y thatthe relay might 'not'pick up, after the train va'cat'es the circuit,becauseithe increase in current'leaking across the ballast'mi'ght causethe energy available at the relay to decrease to a value insulhcient toefiect operation of the relay, to its picked up position.

In'viewof the above-mentioned and other inipo-rtant considerations, itis an object of'our present invention to provide novel and'improvedrailway track'circuit apparatus arranged in such manner that not'onlythe release but "also the picl-z-uplevels'of the circuits are adjustedinaccordance with existing track ballastconditions.

Another object is the provision, ina railway track circuit, of arelay'incorporating means for adjusting its pick-up energylevel inaccordance with ballast conditions existing at the time the trackcircuit becomes "vacated;

A further object is the provision of railway track circuitsincorporating arelay arrangedto 1 conditions i when the "circuit isoccupied as weir as when the-circuit is unoccupied.

An additionalobject'istheprovision of rail'-' way track circuitapparatus arranged in such manner that the release and pick-up values ofthe circuits are maintained substantially constant'regardless ofvariations in track ballast resistance.

The above-mentioned and other important obiects and characteristicfeatures of our invention which will become readily apparent from thefollowing description, are attained in accordance with our invention byincorporating into a track circuit a relay responsive only to suddenchanges in the energy received by the relay and arranged to have bothits release and pick-up values independent of variations in ballastresistance. The relay comprises a movable element which adjusts itsposition in accordance with the energy received by the relay from thetracl circuit, contact means operated by the movable element, andinertia means cooperating with'the movable element for causing operationof the contact means in response to a sudden movement of the movableelement occasioned by a train entering or leaving the track circuit, theinertia means being free to assume a biased position following a suddenmovement of the movable element caused by the train entering thesection, whereby to cause operation of the contact means, upon thefollowing sudden movement of the movable element caused by the trainvacating the section, to be independent of the track ballast resistance.

We shall describe several forms of track circuit apparatus embodying ourinvention, and shall then point out the novel features thereof inclaims.

In the accompanying drawing, Fig. 1 is a diagrammatic view illustratingone form of apparatus embodying our invention. Figs. 2 and 3 arediagrammatic views each illustrating a modified form of the apparatusrepresented in Fig. 1, and each also embodying our invention. In each ofthe several views, similar reference characters have been employed todesignate corresponding parts.

Referring to the drawing, the reference characters l and la designatethe track rails of a stretch of railway track divided by insulatedjoints 2 into an insulated track section DE. Section D-E is providedwith a track circuit comprising a suitable source of energy, such as atrack battery -4,'connected through a resistor 5 to the rails at one endE of the section, and a track relay TR connected across the rails at theother end of the section. RelayTR is of the type arranged to operate itscontacts in response to abrupt and relatively large changes in the eneihgization of the relay windings but not in response to gradual changes inthe relay energization. The relay may, for example, be of thegalvanometer type or, as shown, relay TR. may be of the tractivearmature type.

Relay TR, as shown, comprises a magnetizable core 6 provided with anoperating winding 1, another magnetizable core 8 provided with anauxiliary winding 9, and two movable armature members ill and Ilprovided for and disposed in the magnetic fields of windings l and 9,respectively. Armature I ii is pivoted at l2 and is biased, as by meansof a spring it, into engagement with a backstop I l. The armature isrelatively light so that it has relatively little inertia, hence itresponds readily to the flux created by current in winding 1, and isproportioned to assume different positions according to the energizationof the winding. That is to say, when winding 7 is deenergized, armatureH! is released and rests against its backstop Hi. When winding 7 isenergized, armature ID is attracted and moves against the action ofspring it toward core 6 a distance dependent upon the energization ofthe winding. This characteristic of armature iii may be effected byproviding a relatively large air gap between armature l and core and byproperly proportioning spring l3.

The other armature II is pivoted at l5 and is biased, as by a spring it,into engagement with stop ll. This armature is provided with arelatively heavy counterweight i8 and has a relatively largeinertia,hence it has a relatively slow rate of movement. The armature isoperated away from stop H and is normally positioned in accordance withthe energization of winding 7, by means of an extension i9 secured toarmature ill and engaging extension is secured to armature H. Theextensions it and 20 when in engagement with each other form a circuitcontrolling contact which we shall designate as contact l920.

Armature H is arranged, however, so as at times to respond to flux dueto current in winding 9 and occupya position dependent upon theenergization of the winding. The parts are so proportioned thatarmatures it and E l are caused to assume corresponding positions whenthe same current is present in windings l and ii, and the armatures I llandil are caused to move correspondingly when the current in therespective windings varies slowly. The stops id and ll are positioned tolimit movement of their respective armatures l0 and l I so that whenboth windings i and 9 are deenergized, armature it drops away from core6 a greater distance than armature 5! drops away from core 8, henceunder such conditions contact Iii-29 is opened.

Relay TR has associated therewith a repeater relay TP controlled over acircuit extending from terminal B of a suitable source of current, suchas a battery not shown but havin its opposite terminals designated bythe reference characters B and 0, through contact I 9-46 of relay TR andthe winding of relay TP to terminal C. Relay TP is provided with contactmembers, such as member 22, which may be utilized to control the usualfunctions, such for example as signals, locks, etc., usually controlledby track circuit apparatus, and also has a bifurcated contact member 23which functions as a bridging member of a make-before-break orcontinuity transfer contact combination.

In the normal condition of the apparatus represented in Fig. 1, sectionD-E is rmoccupied 5,the energization available at the relay. Contact 7and only winding l' of relay TB is connected in circuit with the trackrails. The energization of winding 1 causes its associated armature ifto be operated against the action of spring is to a position dependentupon the energy received by the winding from the track rails, and undervacant conditions in the section, armature it is caused to move to aposition wherein extension l9 engages extension 28 and operates armaturell away from its stop ll to a position which corresponds to the positionof armature iii and hence to the energization of winding 5. Contactld2=i accordingly is closed, relay IT is energized and contact member 23is in its upper or front position to close front contact 23-36 thusconnect winding 1 and resistor 26 across the rails of the section at endi) over an obvious circuit.

If, now, a change occurs in the ballast conditions and there is acorresponding change in the energy at the relay end of the circuitavailable to energize relay TR, armature it will be caused to assume adifferent position to correspond to the new energy level in winding Forexample, if the ballast becomes wet and less energ is available toenergize winding 7, armature is will drop away from core 6 to a positionwhere the torque exerted on the armature by spring !3 is just balancedby the torque on the armature due to the magnetic flux created bycurrent in winding 7. In like fashion, should the ballast dry out andmore energy become available for winding 7, then armature luassumes aposition nearer core 5.

These variations in ballast conditions of course occur very gradually,hence the movement of armature lEl to or'from its core 5 to the newposition of correspondence with the energization of winding 7, occurs ata relatively slow rate within the rate of movement of armature l i. Itfollows, therefore, that each movement of armature I0 caused by agradual change in energization of winding 1 eifects a correspondingmovement of armature ll, and the two armatures float up and down andassume positions corresponding to 'l920 of relay TR is thus caused toremain closed for gradual changes in energization of winding 7, andrelay TP remains energized.

When, however, a sudden change is effected in to the energization ofwinding 1, as when a train enters section DE and the established trainshunt lowers the voltage available at the relay end'of the circuit,armature l0 quickly drops away from core 6,'but due to the large inertias5 and slow rate of movement of armature II, the

latter armature slowly follows the movement of the first. Contact |920is, therefore, opened immediately when section D-Ebecomes occupied, andrelay TP releases. During the travel of contact member 23 from its frontpoint 24 to its back point 25, contact 23 bridges both front and backpoints so that back contact 23-25 is closed prior to front contact 23-2being opened. When back contact 23-25 closes, winding 9 is connected inseries with winding 7 across the track rails. If, now, the train shuntis effective and of low resistance, the energization of both windings land 9 may be reduced to a value insufiicient to operate their respectivearmatures l0 and II away from their backstops l4 and I7, hence contact I92ll remains open. However, should the train shunt be of. highresistance, windings 1 and 9 may be energized sufliciently to operatetheir armatures away from their backstops. At this time both windingsare energized inseries so that. the current in the two windings.

to move corresponding distances without change,

in their relative positions upon a change in the energylevel in thewindings,'and asa result contact I920 remains open.

Under the conditions just described, that is, with a train in .section DE and windings I and 9 sufliciently energized to cause operation ofarmatures l0. and H away from their backstops, the ballast conditionsmay vary and in turn vary the energization of windings I and 9. Forexample, if the train enters section D-E when the ballast is dry, andremains in the section during a rainfall, the resistance of the ballastwould then gradually change'from one of relatively high resistance to alower resistance, hence under such conditions less energy Would beavailable to energize windings I and 9 due to the increased leakageacross the ballast. This change in energization of the windings would,of course, occur only gradually so that armatures I and II will becaused to move slowly to positions corresponding to the existingenergization of the windings. The rate of this movement is within thatof the relatively slow moving armature l I, with the result that botharmatures move corresponding distances and do not change their relativepositions, and hence contact |9--20 remains open. It follows, therefore,that armatures l0 and II float apart by moving up or down depending uponthe energization of the windings as determined by the effectiveness ofthe train shunt and the ballast resistance.

When the train vacates section D-E, the energization of windings 1 and 9rapidly increases and winding I0 is moved rapidly toward, core 6.Armature ll does not, of course, move as rapidly, hence contact I92IIbecomes closed, Relay TP, at the end of its relatively short delayinterval, picks up to open its back contact 23-25 and closes its frontcontact 23-24, thereby opening the circuit of winding 9 and insertingresistor 26 in series with winding i. Resistor 29 preferably has aresistance equal to that of winding 9 so that the energization ofwinding 1 is not altered. Theapparatus is, therefore, restored to itsnor mal .condition wherein armature lll assumes a position dependentupon the energization of winding 1, and armature H is likewisepositioned in accordance with the energization of winding 1 due tocontact member I9 engaging extension 20.

From the foregoing, it is readily apparent that track circuit apparatusembodying our invention is.arranged so as to cause operation of itscontacts only in response to sudden changes in energy available at thetrack relaybut not in response to gradual changes, and also that therelay is arranged to adjust both its releaseand its pick-up energylevels to ballast conditions. It is further apparent that if the relayis energized sufficiently to operate its armatures during the intervalthat the section is occupied, the armatures are caused to assumepositions dependent upon either or both the eifectiveness of the trainshunt and the track ballast conditions. It fol: lows that should theballast conditions change during the period of occupancy of the section,the relay will pick up and cause operation of, its contacts when thesection becomesvacated.

In a second form ofapparatus embodying our invention-and represented inFig. 2, we employa,

relay TR] having a sluggish or high inertia member, ll, pivotedcat l5,coupled by a spring 30 to armature l0 and bya spring 3| to armature. 320f relay TP. In the normal condition of the apparatus, as represented inthe drawing, armature I0 assumes a position dependent upontheenergization of winding-l, springs 30 and 3! act on member ll tocause itto move to a position wherein extension wengages extension E9 to closecontact. l9--29, andrelay TP is energized overits-obvious circuitincluding contact 19-40 of relay TP. The parts are soproportioned thatunder vacant conditions in section D-E, armature l0;will move slowlyshould the energy level inwinding I change slowly, and member Hfollowstheslow movement of'armature H! to keep contact i9-20 closed,

When. however, the energy in winding 1 decreases suddenly dueto a trainentering the secengagement with itsbaclzstop H,- the backstops' l4 and Hbeingselocated-thatwhen members ld'and ll rest upon their respectivestops, contact l9--2ii is opened. This condition of the.

apparatus is maintained until section DE becomes vacated, whereupon theenergy in winding increases rapidly and armature H? is operated towardcore 6. Extension iiiaccordingly engages extension to Close contactiii-20, relay TP is energized and picks up its armature 32 to increasethe tension in spring 3| to compensate for the now lessenedtension inspring 89, and back contact 34 of relay T? opens to insert resistor 33incircuit with winding 7. The apparatus accordingly is restored to itsnormal condition as represented in the drawing.

Relay T32, representedin Fig. 3, differs from relay TRE in that movablemember H is supported on a knife-edged bearing member 49, a compression.spring il disposed between extensionslS and biases the extensions apart,but

the two extensions normally are in engagement and contact Iii-+29 isclosed due to theaction of tension spring 35 connected to member andarmature 32 of relay TP, and the gravity bias of member H, which tendsto rotate member H in a counterclockwise direction (as viewed in Fig.3),. Armature as of relay TB?! is arranged, as pointed out heretofore,to adjust its position with respect to the energization of winding 1,and for relatively slow movements of armature l9, correspondingmovements of armature i! are effected so that the relative positions ofthe members. remain th same and, contact closed. clenly decreases,armature it drops, contact iii-2i} opens to deenergize relay TP, andmember l I slowly operates toward its stop l'i. Armature it and memberii normally continue to rest against their respective stops, but shouldthe train shunt be of relatively high resistance, armature 59 might beoperated by winding '5 away from stop 14. The sprin s 3|, and M areselectedso.

i'Q-Zfl; is When the energization in winding 1 sudfective when armatureIt moves slowly,- tokeep armature l9 and member ll separatedsufiicientarmature Ill. The relay accordingly is restored to its normalcondition wherein contact I 9- is maintained closed during relativelyslow movements of armature ID to positions corresponding to the energylevel in winding 1.

From the foregoing, it is readily apparent that we have provided noveland improved forms of railway track circuit apparatus arranged tooperate its contacts only in response to abrupt changes in energyavailable but not to gradual changes, and which apparatus is arranged toadjust both its pick-up as well as the release values in accordance withballast resistance variations. It follows, therefore, that should theballast resistance change considerably during the interval that a trackcircuit is occupied, the apparatus will pick up upon the train vacatingthe section.

Although we have herein shown and described only a few forms of railwaytrack circuit apparatus embodying our invention, it is understood thatvarious changes and modifications may be made therein within the scopeof the appended claims without departing from the spirit and scope ofour invention.

Having thus described our invention, what we claim is:

l. A relay of the direct current tractive type for use with trackcircuits on railroads comprising, a winding, a first pivoted memberdisposed in the field of said winding, means operatively connected withsaid first pivoted member for adjusting it to assume different positionsaccording to the energization of said winding, a second pivoted memberbiased into engagement with said first member and positioned inaccordance with the position of the first member, said second memberhaving a relatively slow rate of movement as compared to the firstmember whereby motion of the first member relative to the second isattained to effect separation or engagement of said members upon suddendecreases or increases respectively in energization of said Winding butcorresponding movements of both members without change in their relativepositions are attained to maintain engagement of said members upongradual changes in energization of said winding, means responsive to asudden decrease in energization of said winding and resultant movementof said first member relative to, and away from, said second member, andmeans rendered efiective by said last-mentioned means for effectingcorresponding movements of said first and second members without changein their relative positions out of engagement with each other forgradual changes in the energization of said Winding.

2. In combination with a magnetizable core provided with a winding andan armature pivoted for swinging movement toward and away from2,347,533- that if relay 'IPis released, the-spring llisejfe said core,means cooperating withsaid armature for causing it to assume a positiondependent upon the energization of said winding, asecond magnetizablecore provided with a second Winding and a second armature pivoted forswinging movement toward and away from said second core, meanscooperating with said second armature for causing it to assume aposition dependent upon the energization of said second winding, the

inertia of said second armature being relatively high with respect tothe'inertia of said first armature, a first member carried by said firstarmature and normally engaging a second member'secured to said secondarmature to position the said second armature in accordance with theenergization of said first winding, a relay .provided with an energizingcircuit completed when said first and second members are in engagement,

circuit means controlled by a front contact of said relay for energizingsaid first winding but not said second winding, for causingcorresponding movements of both said armatures without change in theirrelative positions upon slow changes in energization of said firstwinding and causing a movement of said first armature relative to saidsecond armature to efiect separation of said first and second membersupon a rapid decrease in energization of said first winding, and circuitmeans controlled by a back contact of said relay for energizing bothsaid windings in series, whereby to cause both windings to be effectiveto operate their respective armatures to obtain corresponding movementsof both armatures without change in their relative positions upon slowchanges in energization of said windings and efiective upon a rapidincrease in energization to cause said first armature to move relativeto said second armature to a position wherein said first and secondmembers are in engagement and complete the circuit means over which saidrelay is energized. v

3. In combination with a magnetizable core provided with a winding andan armature pivoted for swinging movement toward and away.

from said core and arranged to assume a position dependent upon theenergy level of said wind-v ing, a movable member pivoted for rotationand having a relatively high degree of inertia with respect to theinertia of said armature, a member secured to said armature for normallyengaging said movable member to position the lattermember inaccordancewith the energization of said winding, a relay energized over a circuitcompleted when said armature member and movable member are inengagement, a coupling between the armature of said relay andsaid-movable member for urging said latter member into engagement withsaid armature memberwhen said relay is energized, whereby to causecorre-' sponding movements of said first armatureand movable memberwithout change in their relative positions upon slight and gradualchanges in the energy level of said winding and effective upon a largeand rapid change in energy level to cause movement of said firstarmature member with respect to said movable member.

4. In a relay, the combination of an electromagnet, a first armaturemember pivoted in the field of said electromagnet and biased away fromsaid electromagnet, means cooperating with said first armature memberfor limiting its movement in response to its bias to a given position,means operatively connected with said first armature member for opposingthe action of said electromagnet on said first armature member wherebyto cause that member to adjust its position in said field in accordancewith the energization of said electromagnet, a second pivoted memberpositioned to be supported by said first armature member and biased awayfrom said electromagnet, means cooperating with said second pivotedmember for limiting its movement in response to its bias to anotherposition to which it is free to move when not supported by said firstarmature member and in which position said second pivoted member is outof engagement with said first armature member in its given position, andinertia means operatively connected with said second pivoted member andhaving a relatively low rate of movement with respect to the rate ofmovement of said first armature member whereby when said second pivotedmember is supportingly engaged by said first armature membercorresponding movements of both members without change in their relativepositions are at tained to maintain such members in engagement upongradual changes in the energization of said electromagnet while motionof said first armature member relative to said second pivoted member isattained to effect the engagement or disengagemerit of such members whenthe energization of said electromagnet abruptly increases or decreases,respectively.

5. In combination, a first winding variably energized from a source ofcurrent, a first armature member pivoted in the field of said firstwind-- ing and biased away from that winding, means cooperating withsaid first armature member for limiting its movement in response to itsbias to a given position, means operatively connected with said firstarmature member for opposing the action on that member of said firstwinding whereb to cause that member to adjust its position in said fieldin accordance with the energization of said first winding, a secondarmature member pivotally positioned to be supported by said firstarmature member and biased away from said first winding, meanscooperating with said second armature member for limiting its move--ment in response to its bias to another position to which it is free tomove when not supported by said first armature member and wherein it isout of engagement with that member in its given position, inertia meansoperatively connected with said second armature member and having arelatively low rate of movement with respect to the rate of said firstarmature member whereby when said first armature member supportinglyengages said second armature member corresponding movements of bothmembers are attained to maintain such members in engagement upon gradualchanges in the current value in said first winding while motion of saidfirst armature member relative to said second armature member isattained to effect the engage ment or disengagement of such members whenthe energization of said first winding abruptly increases or decreases,respectively, a relay energized over a circuit including a contactclosed when said first and second members are in engagement, a secondwinding disposed in magnetic relation to said second armature member,means operatively connected with said second armature member foropposing the action on that member of said second winding whereby tocause that member to adjust its position in accordance with theenergization of said second winding, and an alternate circuit includinga back contact of said relay for simultaneously energizing both saidfirst and second windings from said source for at times causing saidfirst and second members to position themselves in accordance with thecurrent values in said first and second windings respectively.

NORMAN F. AGNEW. PAUL N. MARTIN.

